Carboxyl or anhydride-functional styrene/p-alkylstyrene copolymer, epoxy resin and curing agent

Abstract

A low dielectric constant composition used in electric circuit boards is disclosed. The composition includes (a) 20-99.9 parts by weight of a functionalized syndiotactic styrene/para-alkystyrene copolymer having microfoaming when being cured; (b) 0.01-80 parts by weight of a mixture of epoxy resins; and (c) less than 50 parts by weight of a curing agent.

What is claimed is:  
     
       1. A resin composition for electric circuit boards, comprising: 
       (a) 20-99.9 parts by weight of a carboxyl or acid-anhydride functionalized syndiotactic styrene/para-alkylstyrene copolymer having microfoaming when being cured;  
       (b) 0.01-80 parts by weight of a mixture of epoxy resins; and  
       (c) a minimum amount effective to cure said composition to less than 50 parts by weight of a curing agent selected from the group consisting of an aromatic polyamine, a secondary amine, a tertiary amine, a polycarboxylic acid anhydride and dicyandiamide.  
     
     
       2. The resin composition as claimed in  claim 1 , wherein said functionalized syndiotactic styrene/para-alkylstyrene copolymer is obtained from the co-polymerization with a compound containing a group of carboxyl or acid anhydride, amino, hydroxyl or epoxy. 
     
     
       3. The resin composition as claimed in  claim 2 , wherein said functionalized syndiotactic styrene/para-alkylstyrene copolymer has a weight-average molecular weight ranging from 1×10 4  to 5×10 5 . 
     
     
       4. The resin composition as claimed in  claim 2 , wherein said compound containing said group of carboxyl or acid anhydride is selected from the group consisting of maleic acid, maleic anhydride, acrylic acid, methacrylic acid, citraconic anhydride, itaconic acid, itaconic anhydride, cis-4-cyclohexene-1,2-dicarboxylic acid, cis-4-cyclohexene-1,2-dicarboxylic anhydride and endo-bi-cyclo-2,2,2,1,-5-heptene-2,3-dicarboxylic anhydride. 
     
     
       5. The resin composition as claimed in  claim 1 , wherein said mixture of epoxy resins comprises: 
       (b1) 10-90 parts by weight of a bisphenol polyglycidyl ether; and  
       (b2) 90-10 parts by weight of epoxidized novolak resin.  
     
     
       6. The resin composition as claimed in  claim 5 , wherein said bisphenol polyglycidyl ether has an epoxy equivalent weight ranging from 160 to 4,000. 
     
     
       7. The resin composition as claimed in  claim 6 , wherein said bisphenol polyglycidyl ether has an epoxy equivalent weight ranging from 180 to 200. 
     
     
       8. The resin composition as claimed in  claim 5 , wherein said bisphenol polyglycidyl ether has the following structure:                    
       wherein 
       each of A 1  and A 2  is a divalent monocyclic aromatic radical;  
       n is 0-4; and  
       Y is substituted hydrocarbon radical used for separating A 1  and A 2 .  
     
     
       9. The resin composition as claimed in  claim 8 , wherein said A 1  and A 2  are unsubstituted phenylene or substituted derivatives, wherein the substituent of the derivatives is selected from the group consisting of alkyl, nitro and alkoxy. 
     
     
       10. By The resin composition as claimed in  claim 8 , wherein said Y is a substituted hydrocarbon radical which selected from the group consisting of methylene, cyclohexylmethylene, ethylene, isopropylidene, neopentylidene, cyclohexylidene and cyclopentadecyidene, wherein the substituent is selected from the group consisting of hydrocarbons, oxy, sulfoxy and sulfone. 
     
     
       11. The resin composition as claimed in  claim 1 , which further comprises a filler, wherein said filler is selected from the group consisting of flame retardants, flame retardant aids, and combinations thereof. 
     
     
       12. The resin composition as claimed in  claim 1 , which further comprises a curing accelerating agent. 
     
     
       13. A laminate for printed circuit board, comprising a sheet made from the resin composition as set forth in claim 
       being laminated with a glass cloth.  
     
     
       14. The laminate as claimed in  claim 13 , wherein said glass cloth is impregnated with said functionalized syndiotactic styrene/para-alkylstyrene copolymer having microfoaming when being cured, and said mixture of epoxy resins as set forth in  claim 1 . 
     
     
       15. The laminate as claimed in  claim 13 , which has a dielectric constant of not greater than 3.1 at 1 GHz.